Perhaps there is such a trend because the homosexual agenda (at least the "spiritual" part of it IS gnostic)
Are you familiar with gnosticism? It posits a core utter dichotomy between flesh and spirit, the first being evil or lesser, the second good or higher. This is precisely the approach of the ECUSAn left when it comes to sexuality. What you do with your body is unimportant because the "essence" or spirit of Christianity is a form of disembodied "love". classic gnostic stuff there. I've studied the gnostics pretty thoroughly. My association of this with gnosticism is correct.
Are there perhaps different schools of thought within Gnosticism? I was unaware of the type of which you wrote.